A compound represented by the formula (IV):
(hereinafter, referred to as also compound (IV)), that is, a hexahydrofurofuranol derivative is useful as an intermediate for synthesis of a compound as an anti-AIDS drug (see, WO 01/25240).
As a process for synthesizing a racemic compound represented by the formula (IV), methods described in WO 01/25240, EP 539192-A, WO 2004/002975 and Tetrahedron Letters, 1995, Vol. 36, p. 505 are known. These methods, however, use tributyltin hydride and the like manifesting strong ozone oxidation and toxicity, thus, are not admitted as industrially preferable methods. Further, for obtaining an optically active form thereof (for example, compound represented by the formula (IVa) described later), optical resolution using enzyme is carried out, however, only one of the resulting enantiomers is used for production of an intended substance, and other enantiomer is discarded, leading to inefficiency.
Recently, Tetrahedron Letters, 2001, Vol. 42, p. 2653 suggests a process for directly synthesizing an optically active compound represented by the formula (IVa), and this is the method using an organoselenium compound, thus, it is not admitted as an industrial method.
Further, WO 2004/033462 discloses a method using an optically active form as a raw material, however, the raw material optically active form is expensive, causing an economical problem.
The compound (IV) is usually obtained in the form of a diastereomer mixture with a compound represented by the formula (IV′), however, as an effective method for purifying them, only known are a method of conversion into the corresponding acetate before effecting enzymatic hydrolysis thereof (see, WO 2004/002975), and the like. This method is inefficient since the acetate of the compound represented by the formula (IV′) is discarded.